Thomas a



' UNITED STATES PATENT OFFICE.

THOMAS A. EDISON, OF MENLO PARK, NEW JERSEY, ASSIGNOR TO THE EDISON EL'EOTRIO LIGHT COMPANY, OF NEW YORK, N. Y.

MANUFACTURE OF CARBQNS FOR ELECTRIC LAMPS.

SPECIFICATION formingpart of Letters Patent No. 263,139, dated August 22, 1882,

Application filed August 6, 1880. (No model.) Patented in England September 16, 1880, No. 3,765; in Italy November 6, 1880; in Canada November 11, 1880, No.11,968; in Belgium November 15, 1880, No. 52,890; in Victoria December 13, 1880 No.2,936;

- in Austria-Hungary January 7, 1881; in Queensland February 7, 1881; in New Zealand March 7, 1881, No.510; in Portugal March 31, 1881, N0. 661 in New South Wales April 2, 1881 in Spain April 26, 12581, and in India July 2:2, 1881, No. 535.

To all whom, it may concern Be it known that I, THOMAS A. EDISON, of Menlo Park, in the county of Middlesex and State of New Jersey, have invented a new and useful Method of and Means for Manufacturing Garbons for Electric Lamps, (Case No. 230;) and I do hereby declare that the following is a full and exact description of the same, reference being bad tothe accompanying drawings, and to the letters of referencemarked thereon.

It is desirablein manufacturing carbon slips or filaments of the style generally known as the horseshoe-carbons, for use as the incandescing conductors in electric lights, that they should be carbonized evenly and uni-' formly, and that their shape should be pre served, that the carbonization should be effected without warping or twisting the body of the carbon. As,however, the material con-. tracts largely in the process of carboniz'ation, means are required which, while holding the material in position to avoid twisting or warping, shall at the same time guarantee even and thorough carbonization and permit the material to move so that the inevitable contraction during the'process may proceed without danger of rupturing or otherwise damaging the carbon.

The objectof this invention is to furnish such means; and to that end it consists in the features more particularly hereinafter described and claimed.

In the drawings, Figures 1, 4, 7, and 8 are plan views of carbonizing-plates unitary in principle,but difi'erin g slightly in detail. Figs. 3 and 6 are an edge and a side view, respectively, of a slip or filament ready for carbonization. Figs.2, 5, 9, and 10 are details, more- A is a nickel plate,in which is cutthe groove a,of the shape desired for the finished carbon, and ofa dep'th sufficient to receive the slip or filament S. The coefficientof contractionof the fiber is determined by experiment, and the length of the grooveis made equal to thelength desired for the finished carbon plus the contraction of the material during the process of carbonization. In Fig.1 this extra length is at one end of the groove. to is the groove, enlarged at one end into a small chamber just sufficient to receive one of the enlarged ends 0 of the filamenhwhich is secured therein by a pin, 3. A small wedge, f, vmay also be placed in the chamber to assistin keeping the enlarged end in shape, thepin c passing through both 0 and f. The other end of the groove a. is made into a large chamber, 1), whose length is equal to or greater than the amount of contraction in length of the filament in carbonization. Upon the free end of the slip or filament S the clamp 01 is secured.

The plate A, with the slip or filament secured in position, as described, is covered by a smooth plate or a series may be used, piled one upon another, the smooth under surface of one forming the cover to the one underneath. They are then placed in a suitable nickel case, and on being subjected to the first low heat carbonization and contraction proceed evenly and equally throughout each slip or filament, the contraction drawing up the loose end in the chamber 12, until at'the conclusion of the process the end d is exactly opposite a. .The

cases and plates used are made of nickel, as no other metal stands the high heats necessaryin the final stage of carbonization.

In Fig. 4 the grooye a is shown formed into a chamber, a, at the bow of the horseshoe. In this case the slip Sis laid flatwise in the groove, the ends 0 c fitting into chambers at the end of the groove, upon which weights 0 are laid. By this means the ends are held in position during carbonization, while the contraction is from w to as during the process.

Fig. 7 shows the same construction and method of operation as in Fig, 1, except that while in Fig. 1 the slip is placed edgewise in the groove in Fig. 7 it is placed fiat or sidewise in the groove.

In Fig. 8 the plate A is formed with a chamber in which slides a plate, 0, smaller than the chamber bythesizc of the filament or strip, so that when the plate Oisplaoed in thechamher a groove shall he left, in which is placed the filament or strip, its ends 0 0 resting in chambers fitted for them, and held in place therein by weights 9 g, laid thereon in chambers made therefor. As the filament is thus fastened at the ends,as carbonization proceeds the ensuing contraction pulls the bow toward the ends, forcing the plate 0 toward the end B of A. In all these plans, however, the filament is kept under strain during carbonization, with one or more points fixed against moving, and the contraction proceeds against the strain,which constantly keeps thefilament against or in contact with a former, preserving its shape and obviating any risk of warping or twisting. In all provision is made for keeping flat and in their proper relative position the enlarged ends of the carbon.

' What I claim is- 1. The method of manufacturing carbonsfor incandescent electric lamps, uniform and regular in shape and carbonization, consisting in carbonizing filaments while one or both ends are secured in a certain definite position relatively to the amount of contraction, so that when carbonized and contracted the ends shall be in proper position to each other, substantially as set forth;

2, The improvement in the art of manufacturing ca rhonsforincandcscent electric lamps, consisting in first shaping the slip or filament therefor from carbonizable material and then carbonizing the same while under constant strain, and with one or both ends fixed, substantially as set forth.

8. The carbonizing-plate provided with a groove for shaping the material, and a chamber or chambers, permitting contraction during carbonization,substantially as set forth.

This specification signed and witnessed this 28th day of July, 1880.

THOS. A. EDISON.

Witnesses:

OHAs. BATOIIELOR, G. E. GoUnAUn. 

